Under the landmark U.S. Supreme Court Case of Zablocki v. Redhail, 434 U.S. 374 (1978), the right to marry is fundamental, and any regulation that impairs that right is entitled to "critical examination" by the court.
Since a drug treatment court operates to defer the putative defendant from criminal prosecution, it is conceivable that the court could offer you a "Hobsen's Choice" of: If you get married during the rehab process, we will send your case to the DA for prosecution. Nevertheless, I think that the ACLU might be quite interested in this particular outcome, because it almost certainly would violate your fundamental right to marry.
That said, your atorney is certainly right that the court could make your marriage quite difficult to accomplish -- especially, as you would be forcefd to start a long appeal process which could indeed end up in the High Court. But, if you really want to fight about it, you can, and there is a very important legal precedent that would support your right to marry.
Hope this helps.
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